UPS Technologies Explained
The following is a simple overview to the technologies used. |
On-Line/ Double Conversion Technology
On-line / double conversion technology provides the highest levels of power protection from all mains-borne power problems and is often regarded as the most
dependable type of technology.
The UPS converts the incoming mains AC power to DC power. The DC current provides power to the battery and the inverter, which converts the DC back to AC
and provides a clean, regulated and conditioned AC output to the protected load. The battery is always in circuit and therefore when a mains failure occurs
the battery carries on supplying power to the inverter which means there is no-break in the supply to the protected load and no switching is involved. A
static bypass circuit is incorporated into the UPS which provides a failsafe mechanism, by providing AC mains to the load should the UPS be overloaded or
in the unlikely event of an internal fault.
Online UPS systems are normally recommended when used with generators due to the UPS tolerance to voltage and frequency variations that can be associated
with generators. An RS232 communications port for use with SNMP/ server close down software along with Emergency Power Off (EPO) capability are normally a
standard item on these systems. Power ratings are typically from 700VA to > 600kVA in single module format, with parallel systems and N+1 capability available
from typically 5kVA upwards. Battery extension packs are available to extend the back-up time from a few minutes to a few hours. |
Offline/ Standby Technology
An offline/ standby UPS provides very basic protection against mains-borne problems. AC mains power passes straight through the UPS which has RFI
filtering and limited spike protection provided.
In the event of a mains failure, or the AC mains voltage is outside the UPS operating window, the inverter starts up, a relay closes and allows the
inverter to provide power to the load. Upon AC mains returning the mains output is switched back to mains and the inverter then shuts down. There
are a few milli-seconds break during transfer to/ from the inverter. The output when on inverter is invariably a square wave or stepped sine wave
output.
Offline units typically have power ratings from 250VA to 2kVA. They typically have limited communications capability and whilst relatively cheap
are normally recommended for only a single PC/ workstation type application. |
Line-Interactive Technology
A Line-Interactive UPS provides more superior protection than an offline UPS. However, it still does not provide protection against all mains-borne
problems unlike an on-line double conversion UPS.
These UPS's work in a similar way to an off-line UPS but have superior spike protection than an off-line system. They have a wider tolerance to
voltage variations due to a voltage trimming transformer or similar. This increases the incoming AC mains voltage when it is low and decreases the
incoming AC mains voltage when it is high and prevents the UPS switching to battery power and draining the batteries needlessly. During a mains
failure, or if the incoming mains is outside operating limited the inverter starts up and provides power as described in an offline system. The
output waveform on a line interactive UPS is normally a sine wave output.
Some manufacturers offer a range of battery packs which extend the back-up time from a few minutes to several hours. However, the battery charger
in these UPS systems are limited and depending on how many battery packs are used; it may not be large enough to re-charge the batteries or the
re-charge time could take many days. An RS232 communications port for use with SNMP/ server close down software along with Emergency Power Off
(EPO) capability are normally a standard item on these systems. Power ratings are typically from 400VA to 5kVA and can be offered in either a
tower type or rack-mounted format and whilst not the recommended option, still provide cost-effective protection for server type applications. |
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| UPS Systems |
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UPS systems from 250VA to 4.8MVA. Single & Three phase system. Tower and rack-mount systems available with battery back-up times from a
few minutes to several hours. |
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| Software/ Connectivity |
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The Total Power Systems range of software and connectivity solutions provide real time information which is user friendly and configurable. |
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| Generators |
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Complete range of single or three phase generators available in either open frame or acoustic and weatherproofed sets. Secure containerised generators. |
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| Services |
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A comprehensive range of services are available which includes electrical installation and commissioning for UPS and generators. |
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| Other Products |
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External Maintenance Bypass Switches, DC Power Systems, inverters, Static Switches, Low Voltage UPS, Voltage Stabilisers,
Static Switches along with Customised UPS / Power Systems. |
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